1. Technical Field
The present invention relates to a bearing assembling apparatus assembling a predetermined number of rolling elements within an outer ring, and more particularly, to a bearing assembling apparatus capable of assembling a bearing at a high speed, forming an entire apparatus in compact size, and preventing an excessive unbalanced load from being applied to the outer ring and inserting means when inserting the rolling elements.
2. Description of the Related Art
Needle bearings and roller bearings include bearings of a so-called keystone type; a bag-like installation space open to a center side is formed along an inner surface of the outer ring, and a predetermined number of rolling elements are inserted into the installation space. With respect to this type of bearing, it is possible to prevent the rolling elements from getting out of the above installation space to the center side by bringing the rolling elements into contact with each other, thereby making an inner ring unnecessary.
Conventionally, as apparatuses for assembling the bearings of the type mentioned above, apparatuses provided with inserting means arranged within the outer ring, and feeding means for guiding the rolling elements to the inserting means have been known (See Japanese Unexamined Patent Publication No. 2004-68838, for example).
Specifically, in the above conventional art, a lower holder, a cam member, and an upper holder that constitute the inserting means are arranged in an order inside of the outer ring along a center axis thereof, and a receiving portion is formed over the upper and lower holders, thereby one rolling element fed from the feeding means mentioned above can be received. The upper and lower holders are provided with a guide groove directed toward the installation space from the receiving portion. Further, the cam member mentioned above is rotatable around the center axis of the outer ring, and provided with a cam surface pressing the rolling element to the installation space side on an outer peripheral surface of the cam member.
On the other hand, the feeding means is provided with a guide path which can hold the rolling elements in line, and a pressing means for pressing the rolling elements within the guide path so as to feed the rolling elements to the receiving portion. Specifically, the guide path is formed in a shaft portion extending to an upper side of the upper holder mentioned above, and a lower end portion thereof is open so as to face to the receiving portion. Further, the pressing means is formed in a rod shape, and is arranged above the rolling elements in the guide path.
A parts feeder supplies a predetermined number of rolling elements to the guide path by a supply apparatus, and the rolling elements are fed to the receiving portion one by one by the pressing means. The rolling elements received in the receiving portion are pressed with the cam surface by the rotation of the cam member, and are guided along the guide groove and inserted into the installation space. When the receiving portion becomes empty by one rotation of the cam member, one rolling element is fed to the receiving portion through the guide path, and the insertion of the rolling elements by the rotation of the cam member is repeated until no rolling element is left within the guide path and the receiving portion.
In the conventional art mentioned above, one rolling element is inserted into the installation space by one rotation of the cam member, since there is provided one set of the guide path, the receiving portion, and the cam surface. In other words, in order to insert the predetermined number of rolling elements to the installation space mentioned above, it is necessary to rotate the cam member the predetermined number of times. This makes it difficult to reduce a working time for assembling the bearing.
Further, since the guide path mentioned above holds the predetermined number of rolling elements in line, the guide path is required to be long, and it is necessary to form the pressing means for pressing the rolling elements within the guide path in long size. This makes it difficult to make an entire apparatus in compact size.
Moreover, when the last one of the rolling elements is inserted, it is press-fitted into a gap between two rolling elements at both ends of the rolling elements arranged in line along the inner peripheral surface of the outer ring. Because the outer ring and the cam member are exposed to a stress from one direction due to the pressing force at this time of insertion, a problem arises that an excessive unbalanced load is applied to the outer ring and the cam member. Further, in this case, if relative positions of the gap between the two rolling elements and the guide groove do not match, it is necessary to move the rolling elements arranged in line by the insertion of the last rolling element, which results in a problem of making the load applied to the cam member larger.